Project Description. Abstract: Climate change is projected to increase the frequency and intensity of heatwaves, and heat is already one of the principal weather-related causes of mortality in the U.S. Heat affects certain populations disproportionately, including African Americans, Latinos, city-dwellers, diabetics, the elderly and the poor. The contribution of heatwaves to social disparities in health is an important target for translational research since several preventive interventions exist. Heatwave health warning systems (HHWS), heat island mitigation through tree planting and other measures, and other programs administered by local governments are evidence-based interventions that improve quality of life, foster environmental sustainability, and protect public health during heatwaves. With increasing evidence for accelerated climate change, wider implementation of these programs is needed. This project aims to provide insights into how HHWS and other evidence- based interventions can be translated to other settings to better protect public health and reduce social disparities, thus fostering their more widespread and effective adoption. A multi-disciplinary team, with expertise in epidemiology, sociology, health education, statistics, meteorology, applied public health, and local action and governance, will conduct a mixed-method study in four U.S. cities (Detroit, MI;New York, NY;Philadelphia, PA;and Phoenix, AZ). These cities are at varying stages in implementing HHWS and climate change adaptation programs and include diverse populations with documented racial/ethnic and socio-economic disparities in heat exposure and heat-related health effects. Using qualitative methodology, semi-structured interviews will be undertaken with main stakeholders in the four cities: potential target populations (city residents, predominantly older and of diverse racial/ethnic backgrounds) and implementers of these interventions (government officials representing public health, weather, social and environmental services, among others). The interviews will assess the factors that inhibit or facilitate the translation of the evidence-based interventions. Using quantitative methods, the team will use state-of-the-art epidemiology and meteorology methods to evaluate the triggers of HHWS interventions, investigating ways to make translation of current interventions more effective and easier to understand for the user groups, and communicating specific impacts on population subgroups. This effort will address the availability, reliability and ease of interpretation of HHWS systems by public health officials and the media. We will analyze historical data (1989-2000) in the four cities, comparing daily weather parameters (temperature and heat indices and air mass types) and the degree to which they differ in their associations with excess daily mortality by population group, accounting for air pollution. Through the community action plan, recommendations from the evaluation of results will be shared with relevant authorities from a range of U.S. communities and the public so these research findings will be translated into practice to help achieve the goal of eliminating social disparities in health. PUBLIC HEALTH RELEVANCE: Relevance: Heat exposure can cause illness and death, and heatwaves are increasing in frequency because of global climate change. This research will explore how to better translate evidence-based interventions intended to reduce social disparities in the health impacts of heatwaves (e.g. heatwave health warning systems, tree planting and modifications to the built environment) to other settings. The goal is to encourage the widespread adoption of effective local programs to prevent illness and save lives during heatwaves.